Guard for beveled locking bolts



Oct. 19, 1954 J. C. TIRSCHEL GUARD FOR BEVELED LOCKING BOLTS Filed June 11, 1955 INVENTOR.

WCSTma/M Patented Oct. 19, 1954 STATES OFFICE 1 Claim.

The present invention relates to guards for door locks having beveled locking bolts, and is particularly concerned with the provision of an improved guard for preventing burglars or others from opening with a knife from the outside door locks of the type commercially used on apartment doors having a beveled locking bolt.

One of the objects of the invention is the provision of an improved guard which is simple, capable of economical manufacture, adapted to be applied by persons unskilled in mechanical devices, and adapted to be used on doors of different thickness.

Another object of the invention is the provi sion of an improved guard which will positively prevent the use of a knife on a beveled locking bolt by the insertion of the knife between the door stop and the door frame.

Another object of the invention is the provision of an improved guard of the class described which has its supporting portions of sufficient width so that they will not be engaged or displaced by a knife.

Another object of the invention is the provision of an improved lock guard which requires no preliminary carpenter work on preparation of any recesses in the wood for its reception and which can, therefore, be applied in the shortest possible time to any door which has a slight clearance between the door frame and the edge of the door.

Another object of the invention is the provision of an improved lock guard which may be used for the life of the lock or door without necessity for replacing any of its parts, and which cannot be defeated by inserting a knife or other thin metal member between the door stop and door frame.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the single sheet of drawings accompanying this specification,

Fig. 1 is a fragmentary sectional View taken through a door and door frame and through the lock keeper showing installation of a guard embodying the invention;

Fig. 2 is a fragmentary view in perspective showing the guard and the keeper installed on the door frame;

Fig. 3 is a top edge View of a guard embodying the invention showing in dotted lines the position which one of its parts takes when it is installed;

Fig. 4 is a plan view of the pattern for one of my lock guards.

Referring to Figs. 1 and 2, the present lock guard is particularly adapted to be used with locks of the type indicated at It, having a beveled locking bolt H, which may be withdrawn by means of the knob l2 or by means of a key inserted from the outside in the tumbler barrel 1%.

The locking bolt H is beveled at Hi so that it may be cammed backward by the rounded edge IS on the keeper it as the door is closed, and the locking bolt H is spring pressed to the position of Fig. 1.

The locking bolt has a flat face ii on its opposite side for engaging the inner surface it of the keeper and holding the door closed. The keeper it comprises a box-like metal member having a side Wall 19, an end wall 20 and the upper and lower walls 2!, 22. It has a rectangular opening at 23 for the lock bolt H, and may be open on its rear side, but is provided with an integral attaching apron 24 extending backwardly from its rear side along its front face 25.

Apron 24 is secured to the door frame 26 by screw bolts 21, which are concealed by the edge of the door, and the apron 24 is usually located in a rabbetted recess 28 in the door frame. This makes the face 25 of the keeper is flush with-the inner surface 29 of the door frame.

There is usually a slight clearance between the edge 33 of the door 3i and the surface 29 of the door frame 25. The keeper I6 is also secured in place by wood screws 32 extending into the door trim on the inside.

The door frame 26 usually includes a door stop 33, located on the door frame outside the door to be engaged by the door when the door is closed.

Such locks and door installations are commercially used on apartment doors and burglars often open such doors by inserting a thin knife, such as a tabl knife, atthe point 34 between the door frame 26 and door stop 33.

The knife or other thin blade inserted at 34 must be pushed forward far enough to engage the beveled edge M of the locking bolt II, which can then be cammed backward by pressing downward on the blade which slides on the beveled surface it, until it has caused the locking bolt II to be retracted against its spring.

The guard which is the subject of the present invention is indicated at 35, and is preferably made of sheet metal, such as steel, according to the pattern shown in Fig. 4.

The guard has a relatively wide attaching flange portion 36 bordered by the straight edge 3 31, and the straight end edges 38 and 39. This attaching flange portion 36 is bent at substantially right angles along the line 40, thus providing a door stop engaging portion 4! and a door frame engaging portion 42.

Both of these portions are preferably provided with punched prongs 43, 44 of triangular shape, punched out of the body of the metal and extending backward at right angles. Prongs 43, 44 are spaced from each other above and below was to be out of range of the knife blade used bythe burglar, thus assuring a firm support of the guard on the door frame and stop.

The portion 42 of the guard may have diagonal edges 45, 46, tapering downwardly toward the rectangular tongue 41, which is narrow enough to be inserted in the rectangular hole 23 of the keeper I6.

The tongue 41 is long enough so that it-may be used on doors of different thickness, and the guard is'customarily provided-in a straightcondition except for the bend at 40, and a bend'is made at 48 when the guard is installed on the door frame.

The important and operative-part of the guard for preventing the forcing of the lock is that portion of the tongue 47, which isindicated at'4-9, beyond the bend-48, locatediinside the keeper it.

When the door is closed and locked the guard is also supported by engagement with the door at the door stop 33. The burglar can insert his knife at the point 34 and he can force it forwardly between the body 36 of the guard and the keeper apron 24, but the tongue 49prevents him from engaging the'beveled side of thelocking bolt.

As the guard is simple in construction it may bemanufactured very cheaplyand installed on existing apartment doors at'a minimum amount of expense.

It is very effective in'preventing'burglary of apartments by using a knife blade on such a locking bolt, and may thus save the occupants-from substantial losses by burglary.

While I have illustrated a: preferred embodiment of my invention, many modifications may be made without'departing fromzthe spirit of the invention, and 'I do not wish to'ibe limited to the precise details of construction set'forth,-but desire to avail myself of all changes within the scope of the appended claim.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

In a lock guard for door lock installations of the type having a beveled spring pressed locking bolt, a simple U shaped keeper for the bolt, and a door stop separable from the door jamb by a crack and aligned with the crack at the edge of the .door, an improved guard preventing tampering with the boltwith a thin instrument, comprising a thin sheet metal member having a flat body to be located between the door edge and the jamb adjacent the bolt, said body when mounted extending from the door stop to the inside of the keeper, and having an elongated flange capable of being bent at any point of its length at rightangles to said body to accommodate various thicknesses of door jambs so that the bent end portion of said flange will extend into the keeper on the side toward the door frame, said flange when bent into the keeper engaging any instrument inserted "between the .jamb-and the guard from the outside and preventing the instrument from engaging the beveled side of the bolt, said body also having a preformed flange at right'angles to the body and when mounted extending inwardly toward the door in front of the door stop and being capable of preventing the insertion of an instrumentbetween said body and-the edge of the .door adjacent the bolt, said body being widened in a vertical direction above, below and away from rsaidelongated bendable flange to increase the stability ofuthe guard, and having'pressed out prongs at its widest portion adjacent its upper and'lower .edgesadapted to engage thedoor jamb and the :stop and serving as'a further 'obstruction'of an'instrument between the jamb and the-guardby keeping such instruments away from the beveled bolt.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 941,877 Hosch Nov. 30, 1909 1,919,739 'Minzenmayer July 25, 1933 2,255,860 Riedel :Sept. 16', 1941 2,484,024 Garberding Oct. 11, 1949 

